WASHINGTON - A semi-automatic pistol found near the scene of a gun battle in Mexico where five people died, including a Mexican beauty queen, has been traced to a former federal gun agent in Minnesota who was part of the government's controversial Fast and Furious border gun-tracking operation.

The Justice Department's inspector general has confirmed that it is investigating allegations that an FN Herstal Five-seven handgun tracked from the area of a Nov. 23 shootout in Sinaloa was linked to George Gillett Jr., who oversaw Operation Fast and Furious from October 2009 to April 2010.

Gillett played a central role in a similar Twin Cities gun sting a decade ago that was shut down after several government-tracked guns were connected to violent gang crimes. He later worked in Arizona and has offered himself as a witness in the Republican-led congressional probe of Operation Fast and Furious, which led to a U.S. House contempt vote in June against U.S. Attorney General Eric Holder.

The new probe, confirmed in a Dec. 21 Justice Department letter obtained by the Star Tribune, focuses on alleged purchases of at least three firearms by Gillett while he was the assistant special agent in charge of the Phoenix field office of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). He has since been reassigned to Washington.

While the ATF has been criticized for losing track of U.S.-sold guns trafficked in Mexico, Gillett's case represents the first time that a weapon recovered south of the border has been tied to an official with the ATF. The powerful Five-seven was limited to military personnel and law enforcement until 2004. The ATF has said the weapon is a favorite of Mexican drug cartels, and those smuggled across the border can command top dollar in Mexico.

Gillett, a former street agent tracking so-called straw gun buyers in the Twin Cities, said Wednesday that on the advice of counsel, he could not comment.

More ties to Fast and Furious

The investigation comes amid heightened congressional scrutiny of arms trafficking and gun crimes in the wake of the Sandy Hook Elementary School massacre in Connecticut.

ATF records show that Gillett's gun was one of at least two recovered in the vicinity of the fatal shootout between the Mexican military and drug cartel members in Sinaloa. The other was an AK-47 traced to Uriel Patino, a leading suspect in the Fast and Furious operation, which has been linked to the 2010 shooting death of U.S. Border Patrol agent Brian Terry.

Congressional Republicans rallied around Terry's death, which they blamed on lax ATF oversight within the Obama administration.

But some law enforcement officials point to gun laws that make it difficult for federal agents to interdict legally purchased weapons until they "walk" into the criminal underworld.

In Operation Fast and Furious, the ATF was faulted for mistakes in a "gun walking" operation tracking nearly 2,000 weapons that eventually disappeared or fell into the wrong hands along the Mexican border in 2009 and 2010. An earlier inspector general report found Gillett's supervision "seriously deficient."

The latest revelations involve Gillett's own personal guns, allegedly purchased using inaccurate addresses. ATF records show that in two of the gun purchases, which include the pistol found in Sinaloa, Gillett listed the address of the Phoenix ATF office. On the third, he listed the address of a local shopping center.

U.S. Sen. Charles Grassley of Iowa, the ranking Republican on the Judiciary Committee, singled out Gillett in a Dec. 19 letter to the inspector general's office, noting that it is a felony offense to falsify a federal gun transaction record known as Form 4473. Grassley, one of the leading congressional investigators in the Fast and Furious case, emphasized that many of the suspected gun runners arrested in the operation were charged with lying on the form.

"This information's implications and its ability to undermine public confidence in the integrity of ATF operations cannot be overstated," Grassley wrote to the inspector general. "Your office needs to work swiftly."

'I didn't do anything criminal'

The pistol found in the Sinaloa gunfight was purchased at Legendary Arms, a Phoenix gun store, on Jan. 7, 2010, while Gillett was the No. 2 man of the local ATF office. The gun is listed in an ATF trace requested by Mexican authorities as being involved in an attempted homicide.

The suspected drug battle took the lives of five people, including a Mexican soldier and Sinaloa beauty queen Maria Susana Flores Gamez. Mexican officials said she likely was used as a human shield by the drug traffickers when they burst out of a car in a hail of bullets.

Gillett acknowledged in an interview with CBS News last month that the Belgian-made pistol found in Sinaloa was his but that he had advertised it on the Internet and sold it legally for about $1,100 a year before to a U.S. citizen in Arizona.

According to Grassley's office, Gillett and other ATF officials involved in the Fast and Furious case are under review by the ATF's Professional Review Board. An ATF spokesman did not respond to a request for comment.

Gillett is one of two agents from the Minnesota ATF office who played supervisory roles in Fast and Furious. The other is David Voth, who once described the operation as "the tip of the ATF spear" in U.S.-Mexico firearms trafficking.

Voth, however, was not involved in the controversial Twin Cities' gun-tracking operation, which was shut down in 1996 at the request of then-U.S. Attorney David Lillehaug, who became concerned about the ATF's ability to track and control the guns.

At the time, the ATF operation was focused on a south Minneapolis gun store run by Mark Koscielski, a cooperating witness who was simultaneously battling residents and city officials trying to close his business.

The mayor of a traditionally liberal Wisconsin city has ordered the removal of a cemetery's monuments to Confederate soldiers, saying the Civil War was "a defense of the deplorable practice of slavery" and "an act of insurrection and treason."